File Sharing Service and SMB Protocol
FILE SHARING SERVICE An online file sharing service provides a way to store and access information, such as documents, data, photos and video, in the cloud rather than storing the information locally on a device hard drive or removable media. The advantage of online file sharing services, such as Dropbox, is that companies using the service do not have to support and maintain the data themselves. The information stored in an online file sharing service can be accessed from any device that has an Internet connection, including smartphones and tablet PCs, and by anyone who is given data access rights. The best online file sharing services not only provide a competitive price, but also competitive features. They should offer tracking tools and make the security of your files a priority. Below is the criteria we used to evaluate the top peer to peer file sharing (P2P file sharing) services. 'Service Features' : When looking for the best secure file transfer service for your business, you must consider the features the service offers. We determined the maximum number of sends, the maximum storage space provided and the maximum file size limit for each service. We also checked to see if they deliver all file types, whether multi-user plans are available, how many days the files remain available, if they can send large files online and if a MS Outlook plugin is provided. 'Tracking' : Tracking tools are necessary during a large file transfer to clients or other employees. Top file sharing sites provide a confirmation receipt when your files have been successfully uploaded and when they have been successfully delivered. Some services provide an audit log, which managers can use to view and monitor their employees' file-sharing activity. 'Security' : The best file sharing service should also be a secure file sharing service. We looked for services that encrypt every file transfer and offer password protection to keep your files safe while they are stored on the company’s servers. Many of the best services also provide an isolated storage facility as an extra safety precaution. : Help & Support Online file sharing services should be straightforward and easy to use. However, if problems or questions do arise, it is imperative that help is available. We looked for services that provide email and telephone support, along with a FAQs and a knowledgebase located on their websites for additional assistance. Online file sharing services are a benefit to businesses that need to transfer big files around the world. These large file sharing services not only save you time, but they can save you money and prevent frustration as well. Whether you are looking for a basic file sharing service or one filled with extra features (liek big file transfer), one of the online file sharing services in our review is sure to help streamline your business’s file-sharing activities. SMB Stands for "Server Message Block." SMB is a network protocol used by Windows-based computers that allows systems within the same network to share files. It allows computers connected to the same network or domain to access files from other local computers as easily as if they were on the computer's local hard drive. Not only does SMB allow computers to share files, but it also enables computers to share printers and even serial ports from other computers within the network. For example, a computer connected to a Windows network could print a document on a printer connected to another computer on the network, as long as both machines support the SMB protocol. SMB Stands for "Server Message Block." SMB is a network protocol used by Windows-based computers that allows systems within the same network to share files. It allows computers connected to the same network or domain to access files from other local computers as easily as if they were on the computer's local hard drive. Not only does SMB allow computers to share files, but it also enables computers to share printers and even serial ports from other computers within the network. For example, a computer connected to a Windows network could print a document on a printer connected to another computer on the network, as long as both machines support the SMB protocol. Though SMB was originally developed for Windows, it can also be used by other platforms, including Unix and Mac OS X, using a software implementation called Samba. By using Samba instructions, Mac, Windows, and Unix computers can share the same files, folders, and printers. This is great for those Windows-based office networks where there is a graphic designer who refuses to use anything but a Mac and a tech guy who does everything on his Linux machine. SMB Protocol Variants Since the inception of SMB, many protocol variants have been developed to handle the increasing complexity of the environments that it has been employed in. The actual protocol variant client and server will use is negotiated using the negprot SMB which must be the first SMB sent on a connection. The first protocol variant was the Core Protocol, known to SMB implementations as PC NETWORK PROGRAM 1.0. It could handle a fairly basic set of operations that included: *connecting to and disconnecting from file and print shares *opening and closing files *opening and closing print files *reading and writing files *creating and deleting files and directories *searching directories *getting and setting file attributes *locking and unlocking byte ranges in files Security The SMB model defines two levels of security: Share level. Protection is applied at the share level on a server. Each share can have a password, and a client only needs that password to access all files under that share. This was the first security model that SMB had and is the only security model available in the Core and CorePlus protocols. Windows for Workgroups' vserver.exe implements share level security by default, as does Windows 95. User Level.Protection is applied to individual files in each share and is based on user access rights. Each user (client) must log in to the server and be authenticated by the server. When it is authenticated, the client is given a UID which it must present on all subsequent accesses to the server. This model has been available since LAN Manager 1.0. 'HISTORY Barry Feigenbaum originally designed SMB at IBM with the aim of turning DOS "Interrupt 33" (21h) local file access into a networked file system. Microsoft has made considerable modifications to the most commonly used version. Microsoft merged the SMB protocol with the LAN Manager product which it had started developing for OS/2 with 3Com around 1990, and continued to add features to the protocol in Windows for Workgroups (c. 1992) and in later versions of Windows. SMB was originally designed to run on top of the NetBIOS/NetBEUI API (typically implemented with NBF, NetBIOS over IPX/SPX, or NBT). Since Windows 2000, SMB runs, by default, with a thin layer, similar to the Session Message packet of NBT's Session Service, on top of TCP, using TCP port 445 rather than TCP port 139—a feature known as "direct host SMB" .At around the time when Sun Microsystems announced WebNFS,Microsoft launched an initiative in 1996 to rename SMB to Common Internet File System (CIFS), and added more features, including support for symbolic links, hard links, larger file sizes, and an initial attempt at supporting direct connections over TCP port 445 without requiring NetBIOS as a transport (a largely experimental effort that required further refinement). Microsoft submitted some partial specifications as Internet-Drafts to the IETF, though these submissions have expired. The Samba project originated with the aim of reverse engineering the SMB protocol and implementing an SMB server to allow MS-DOS clients to use SMB to access files on Sun Microsystems machines.Because of the importance of the SMB protocol in interacting with the widespread Microsoft Windows platform, Samba became a popular free implementation of a compatible SMB client and server for interoperating with non-Microsoft operating systems. Microsoft introduced SMB2 with Windows Vista in 2006, and later improved on it in Windows 7, with subsequent major revisions of 2.1 and 3.0 as of 2012. FEATURES The SMB "Inter-Process Communication" (IPC) system provides named pipes and was one of the first inter-process mechanisms commonly available to programmers that provides a means for services to inherit the authentication carried out when a client first connected to an SMB server. Some services that operate over named pipes, such as those which use Microsoft's own implementation of DCE/RPC over SMB, known as MSRPC over SMB, also allow MSRPC client programs to perform authentication, which over-rides the authorization provided by the SMB server, but only in the context of the MSRPC client program that successfully makes the additional authentication. The design of Server Message Block version 2 (SMB2) aims to mitigate this performance-limitation by coalescing SMB signals into single packets. SMB supports opportunistic locking — a special type of locking-mechanism — on files in order to improve performance. SMB serves as the basis for Microsoft's Distributed File System implementation.